DE102008018622B4 - Method for operating a brake system and brake system for a commercial vehicle - Google Patents

Abstract

Method for operating a parking brake (10) with parking brake actuators (24, 24 ', 24'',24''', 25, 25 ') and a service brake (20) comprising a brake system (34) of a commercial vehicle (12), wherein in Case of a malfunction of the service brake (20), the parking brake (10) supports a braking of the commercial vehicle (12), wherein the parking brake actuators (24, 24 '', 24 ''', 25, 25') of the parking brake ( 10) to be applied braking forces via an ABS control loop and the Feststellbremsaktuatoren (24, 24 ', 24'',24''', 25, 25 ') are actuated according to the particular applied braking forces, characterized
- That a plurality of vehicle axles (32, 32 ', 32'') in any combination by the parking brake (10) can be braked and
- That only the vehicle axles (32, 32 ', 32'') are braked by the parking brake (10), which are affected by the defect of the service brake (20).

Description

The invention relates to a method for operating a parking brake comprising parking brake actuators and a service brake comprehensive braking system of a commercial vehicle, wherein in the event of a defect of the service brake, the parking brake supports a braking of the commercial vehicle, said determined by the Feststellbremsaktuatoren the parking brake forces via an ABS control loop and the parking brake actuators are operated in accordance with the determined applied braking forces.

The invention further relates to a brake system of a commercial vehicle with a parking brake comprehensive parking brake and a service brake wherein in case of failure of the service brake, the parking brake supports a braking of the commercial vehicle, wherein the parking brake comprises an electronic control unit, which is adapted to an ABS control loop for operating the parking brake actuators perform.

Commercial vehicles have a brake system that includes a service brake and a parking brake. The service brake of the commercial vehicle must be designed so that the commercial vehicle can be stopped safely. This is especially true in case of failure of the service brake, wherein the achievement of a certain, vehicle-dependent minimum braking effect is prescribed even in case of defect.

For this purpose, for example, separate service brake circuits of the service brake can be designed accordingly, but this causes an increased construction costs.

From the DE 10 2005 043 608 A1 is also known to support the defective service brake by closing the parking brake in their braking effect. In particular, the spring-loaded cylinders of the parking brake are vented according to a predetermined time-pressure-separation line.

The DE 199 42 533 A1 describes a way to integrate an ABS control loop in a parking brake to prevent wheel lock when using the parking brake as an emergency brake.

From the WO 2004/054862 A1 It is already known to apply a "select-low" principle to the braked by the parking brake while driving wheels to increase vehicle stability.

Deviating from the "select-low" principle is in the DE 101 55 536 A1 describes a parking brake, in which during an auxiliary braking, that is a failure of the service brake, on a braked by the parking brake vehicle axle different brake pressures are allowed to cause a yaw moment.

The DE 197 38 877 A1 shows an electric parking brake, in which actuators of the parking brake can be applied by means of an electromotive actuator.

From the DE 60 2004 000 867 T2 a parking brake is known in which the vehicle can be braked in the event of malfunction of the service brake by pressing the parking brake.

The DE 10 2006 041 008 A1 describes a pneumatic vehicle brake system, in which the braking effect of a recognized as failed failure brake circuit is automatically replaced by the engagement of the parking brake.

The object of the present invention is to improve the method with regard to the braking effect in terms of safety.

This object is solved by the features of the independent claims.

Advantageous embodiments of the invention are indicated in the dependent claims.

The invention is based on the prior art in that a plurality of vehicle axles can be braked in any combination by the parking brake and that only the vehicle axles are braked by the parking brake, which are affected by the defect of the service brake. If only individual vehicle axles or vehicle wheels are affected by the defect of the service brake, then the reduced braking effect of the service brake can be at least partially compensated, without having to accept other disadvantages. In particular, the ABS functionality of the further braked by the service brake vehicle axles or vehicle wheels can be maintained unrestricted, which can be advantageous in terms of the control speed of the ABS control loop used, since the dynamic adjustment of the braking force of the parking brake operates somewhat slower than the service brake. The dynamic adaptation of the braking effect exerted by the parking brake via an ABS control loop results in an improvement of the braking effect independent of the road conditions even in the event of a malfunction of the service brake system, which may be, for example, a pneumatically operated brake system with an ABS functionality. In particular, an ABS Artige brake support for commercial vehicles are maintained even with a defect of the service brake, so that even with an unloaded commercial vehicle, the vehicle wheels do not block.

Preferably, it is provided that the parking brake actuators comprise spring brake cylinders, wherein the applied braking forces are determined as ventilation rates for the spring brake cylinders and that the parking brake actuators are vented according to the determined ventilation rates. Spring brake cylinders are particularly well suited for the dynamic adaptation of the applied braking forces via an ABS control loop.

Alternatively, it can be provided that the parking brake actuators comprise electric motor-applied parking brake actuators, wherein the applied braking forces are determined as control pulses for the electric motor zuspannbaren Feststellbremsaktuatoren and that the electric motor zuspannbaren Feststellbremsaktuatoren be operated according to the specific control pulses. Even if the parking brake has electric brake actuators zuspannbare brake cylinder is a dynamic adjustment of the applied braking forces possible.

It can be provided that the ABS control loop comprises an individual control for a braked by the parking brake vehicle, wherein the applied braking force for the braked vehicle is determined separately. By adapting the applied braking force to the respective vehicle wheel, for example via the adjustment of the ventilation rate of a spring brake cylinder, an optimal braking effect of the parking brake is also possible for different vehicle wheels on different road conditions.

Alternatively it can be provided that the ABS control loop comprises a "select low" control for a braked by the parking brake vehicle axle, wherein the applied braking force of Feststellbremsaktuatoren the braked vehicle axle is determined by the highest applied braking force at which no vehicle wheel braked on the Vehicle axle blocked. Although the transferable braking torque is reduced by the axle-by-axle adaptation of the braking force to be applied, for example via the adaptation of the bleeding rate of spring brake cylinders, in return the lateral acceleration occurring on the commercial vehicle is minimized by vehicle wheels of varying degrees braking on one axle.

However, it is preferably provided that the ABS control loop comprises a modified individual control for a vehicle axle braked by the parking brake, wherein the applied braking force of the parking brake actuators of the braked vehicle axle is determined by the highest braking force to be applied, at which no vehicle wheel is yet blocked on the braked vehicle axle, and this applied braking force may be exceeded by the rest of the parking brake actuators on the same braked vehicle axle by a predetermined tolerance. This modified individual control allows a maximum braking effect of the parking brake up to a blocking of the vehicle wheels analogous to the individual control or up to a maximum lateral acceleration. The modified individual regulation therefore represents a kind of mixed form between the individual regulation and the "select low" regulation.

Advantageously, it is provided that the ABS control loop takes into account speed or rotational frequency characteristics of the vehicle wheels to be braked. The speed or rotational frequency characteristics of the vehicle wheels to be braked are typical input variables of an ABS control loop.

The brake system according to the invention builds on the prior art, characterized in that the parking brake is designed to brake several vehicle axles in any combination. On this basis, the advantages and special features of the method according to the invention are also implemented in the context of a device.

This can advantageously be further developed by the fact that the parking brake is designed to simultaneously exert different braking forces via the parking brake actuators. If a vehicle wheel is prone to jamming, the braking force exerted by the parking brake actuator may also be subsequently reduced slightly to free the wheel.

The invention will now be described by way of example with reference to the accompanying drawings by way of particularly preferred embodiments.

Show it:

1 a brake system of a commercial vehicle in a schematically simplified representation;

2 a part of a brake system of a commercial vehicle in a schematically simplified representation;

3 a part of a brake system of a commercial vehicle in a schematically simplified representation;

4 a schematic representation of a commercial vehicle with a brake system according to the invention;

5 a flowchart for explaining the method according to the invention and

6 a time sequence of an ABS control loop.

In the following drawings, like reference characters designate like or similar parts.

1 shows a brake system of a commercial vehicle in a simplified schematic representation. A commercial vehicle 12 , which is indicated as a simple driver's cab, includes a brake system 34 , whose components are shown in a schematic way. The commercial vehicle 12 has vehicle axles 32 . 32 ' with vehicle wheels 28 . 28 ' . 28 '' . 28 ''' on each of which a parking brake actuator 24 . 24 ' . 24 '' . 24 ' , which is shown in each case as a spring brake cylinder, and a wheel speed sensor 56 . 56 ' . 56 '' . 56 ''' assigned. Instead of the illustrated pneumatically actuated spring brake cylinder 24 . 24 ' . 24 '' . 24 ' can the brake system 34 also have electromotive parking brake actuators for generating the parking brake force, wherein the brake pads with changed current flow through the actuator, which may be an electric motor, for example, to the wheel drum or the disc brake of the vehicle wheel 28 . 28 ' . 28 '' . 28 ''' pressed or lifted off these. For example, with a reduction in the energization of the actuator, the brake pad can be pressed against the disc by an energy-storing element, such as a spring, realizes this contact pressure.

Furthermore, at the front axle 32 of the commercial vehicle 12 ABS modulators 54 . 54 ' in a first service brake circuit 18 located. Separately, there is a second service brake circuit 18 ' , the rear axle 32 ' of the commercial vehicle 12 brakes, wherein for the sake of simplicity in the second service brake circuit 18 ' no ABS modulators are shown. The first service brake circuit 18 and the second service brake circuit 18 ' are via valve modules 36 . 36 ' operated, in turn, via a CAN bus 30 from another electrical control unit 22 are electrically controlled. The other electrical control unit 22 is again with a service brake value transmitter 16 electrically coupled, for safety reasons, pneumatic backup lines are still provided, via which the valve modules 36 . 36 ' directly from the service brake value transmitter 16 are controllable. The supply of service brake circuits 18 . 18 ' via a compressor 46 and a compressed air treatment plant 48 , wherein the processed compressed air in storage tanks 50 is stored. There is also a trailer control module 58 provided that a pressure supply connection 60 for a trailer and a trailer control connection 62 provides. The in the service brake circuits 18 . 18 ' used spring brake cylinder 24 . 24 ' . 24 '' . 24 ' have, in addition to the connection to the service brake, a second port through which the parking brake functionality of this combination cylinder is available. About pressure lines, these connections are also with one of an electrical control unit 14 controllable valve module 36 '' coupled. The electrical control unit 14 , or the valve module 36 '' , is designed bistable and self-holding and suitable, the parking brake pressure in the spring brake cylinders 24 . 24 ' . 24 '' . 24 ' to determine and control a trailer test function. Furthermore, the electrical control unit 14 together with the valve module 36 '' in the compressed air treatment plant 48 or an unillustrated ABS control module integrated or partially integrated. In the 1 shown piping is to be understood only symbolically. The exact pipe routing depends on whether the spring brake cylinder 24 . 24 ' . 24 '' . 24 ' should be controlled individually or by axle. The electrical control unit 14 is via an electrical line with a manual control unit 38 , which may have a battery coupled. via the hand control unit 38 is the parking brake of the commercial vehicle 12 actuated. Furthermore, it may also include a wake-up function to enable the actuation of the parking brake with the ignition off. The hand control unit 38 can also support a test feature that allows you to separately open the parking brake of a trailer. Error messages of the brake system 34 can via a signal lamp 44 be issued. The signal lamp 44 is to be understood symbolically as output means. A tachograph 40 is about the information of the wheel speed sensors 56 . 56 ' . 56 '' . 56 ''' operable by the CAN bus 30 receives, and has a connection to a vehicle CAN 42 on. The commercial vehicle 12 also includes an option, not shown, for receiving external information stored in the CAN bus 30 can be fed. The monitoring of the pressures in the various separate pressure circuits via pressure sensors 52 ,

2 and 3 show a part of a brake system of a commercial vehicle in a simplified schematic representation. In particular, in the 2 and 3 only the front axle 32 of the commercial vehicle 12 shown with the components arranged therein. In particular shows 2 a Embodiment with through the valve module 36 '' separately controllable spring brake cylinders 24 and 24 ' because separate piping in the 2 are shown explicitly. In 3 is a way to connect other unillustrated spring brake cylinder via a pressure connection 76 to the valve module 36 '' indicated.

4 shows a schematic representation of a commercial vehicle with a brake system according to the invention. The illustrated commercial vehicle 12 has three vehicle axles 32 . 32 ' . 32 '' at each of which spring brake cylinder 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' arranged in pairs. The spring brake cylinders 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' belong to a brake system 34 that a service brake 20 and a parking brake 10 includes. The spring brake cylinders 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' belong as a combination cylinder while both the service brake 20 as well as to the parking brake 10 , where the respective control devices 14 . 22 the parking brake 10 or the service brake 20 over the CAN bus 30 coupled together. Occurs in a service brake circuit of the service brake 20 a defect, for example on the front axle 32 of the commercial vehicle 12 , so are the spring brake cylinders arranged there 24 . 24 ' no longer by the service brake 20 actuated. A defect may be, for example, the pedal break of the service brake valve, whereby actuation of the electrical and pneumatic control circuit of the service brake is no longer possible. A stepped braking of the vehicle can then take place with the involvement of the parking brake. Is the parking brake delay additionally controllable via wheel speed sensors 56 . 56 ' . 56 '' . 56 ''' , so the vehicle can be safely delayed or brought to a standstill without the wheels lock. The other electrical control unit 22 shares the electrical control unit 14 the parking brake 10 the error over the CAN bus 30 in the form of a control signal 26 with what is indicated in the form of an arrow. Will a stunt of the commercial vehicle 12 over the service brake 20 requested, so can the other control unit 22 due to the defect only on the axles 32 ' . 32 '' arranged spring brake cylinder 24 '' . 24 '' . 25 . 25 ' drive. The further control unit 22 is now over the CAN bus 30 a control signal 26 to the control unit 14 out, causing the parking brake 10 is initiated on the axis 32 arranged spring brake cylinder 24 . 24 ' to vent, that is the parking brake on the vehicle axle 32 to press. One is in the control unit 14 integrated ABS control loop, which in connection with the 6 will be explained in more detail. Furthermore, a signal is sent to the ABS control of the service brake in order to adapt the brake pressure of the service brake and the evaluation of the rotation rate sensors to the slow-acting ABS control loop of the parking brake. Both systems the electrically actuated ABS-capable service brake system and the electrically actuated parking brake thus exchange internal data via an electrical serial communication line. This exchange can be monitored by further control devices, not shown here, for example a vehicle management computer. A time out of the communication signal over a longer period of time and detectable by one of the electric microcontroller units of the parking brake or the service brake is evaluated, in particular after the unsuccessful attempt to resume the electrical communication, as a defect of the ABS-capable service brake.

5 shows a flowchart for explaining the method according to the invention. Starting from step 100 , the normal operation of the commercial vehicle, will be in step 102 checks whether the service brake has a defect. If no, go to step 100 continued. If yes, go to step 104 continues and checks whether braking was initiated via the service brake. If no, go to step 104 continued. If yes, go to step 106 continued and started the ABS control loop for the electrically controlled parking brake. The ABS control loop of the parking brake is rather sluggish due to the large storage volume of spring storage, which is why an inclusion of the lead and the lag in the form of reference speeds, which are above the theoretical slip speeds, are taken into account. The explicit procedure is related to 4 already described, while the exact configuration of the ABS control loop in connection with 6 will be described in detail below.

6 shows a timing of an ABS control loop. Plotted on the x-axis is the time, on the y-axis of 6a ) the velocity v, on the y-axis of 6b ) the acceleration a of a braked vehicle wheel and on the y-axis of 6c ) The contact pressure p of the braked vehicle associated spring brake cylinder, that is, the force applied by the spring brake cylinder force per area. The contact pressure p is thus not identical to the prevailing in the spring brake cylinder spring accumulator chamber pressure, which biases the spring. If instead of the contact pressure p in picture 6c ) the real prevailing spring accumulator chamber pressure are applied, the graph is to be mirrored on the x-axis and to move upwards by about 8.5 bar, since at about 8.5 bar, the wheel is free. It should also be noted that a deceleration of the wheel typically starts at 4 bar. The contact pressure p, or the associated force can be determined via the measurement of the spring accumulator chamber pressure. Will one Braking the vehicle causes and at the same time there is a defect in the service brake, so the braked the vehicle wheels associated spring brake cylinder are vented, the contact pressure p according to a curve 74 increases. This is synonymous with a slow closing of the spring brake cylinder by lowering the spring accumulator chamber pressure and thus a mirror image of the usual brake actuation of the service brake which builds pressure in the brake cylinder, so increased to achieve a braking effect and to delay the wheel. At a time t ₁ 78 is a vehicle speed 64 , which falls due to the onset of braking effect, from the braked by the parking brake vehicle wheel by a reference speed 68 different. The reference speed 68 is in each case by a fixed amount lower than the vehicle speed 64 , This is in 6a ) at the time t ₁ 78 at the interface between the limit speed 68 and a wheel speed 66 visible, noticeable. From this point, the pressure in the spring brake cylinder is kept constant and as a result, the contact pressure remains 74 until a time t ₂ 80 constant, where due to a Radumfangsbeschleunigung 72 represented in 6b ), an incipient locking of the vehicle wheel, by a slip speed 70 marked, can be determined. In order to prevent complete blockage of the braked by the parking brake vehicle wheel is from the time t ₂ 80 until a time t ₃ 82 the pressure in the spring brake cylinders increased again to the contact pressure 74 lower again. As a result, the so far negative Radumfangsbeschleunigung is growing 72 from the time t ₂ 80 again and at the time t ₃ 82 again the specifiable value -k. In the time interval t ₃ 82 to t ₄ 84 increases the wheel circumference acceleration 72 from a value -k over a vanishing wheel circumference acceleration 72 up to a value + k. At the zero crossing of the Radumfangsbeschleunigung 72 the associated wheel speed has its maximum difference to the vehicle speed 64 it reaches and approaches slowly again. Reaches the wheel circumference acceleration 72 the value + k, the contact pressure by venting the spring brake cylinder until a time t. ₅ 86 increases, where the Radumfangsbeschleunigung goes again by the value + k. Since the Radumfangsbeschleunigung at the time t ₄ 86 with + k still greater than zero, the wheel speed is approaching 66 continue the vehicle speed 64 at. The contact pressure 74 of the spring brake cylinder is up to a time t. ₆ 88 , in which the wheel circumference acceleration reaches the positive value k ₂ <+ k, kept constant. Upon reaching the positive small Radumfangsbeschleunigung k ₂ at time t ₆ , the wheel speed 66 again almost the vehicle speed 64 approximated. In order not to unnecessarily waste braking effect, therefore, from the time t ₆ 88 until a time t ₇ 90 the contact pressure 74 the spring brake cylinder increases by venting again and the ABS control cycle begins again at the time t ₇ 90 analogous to the time t ₁ 78 , where the plateau interval between the time t ₁ 78 and the time t ₂ 80 can be omitted, which is why a time t ₈ 92 technically equivalent to the time t ₃ 82 is shown.

LIST OF REFERENCE NUMBERS

10

Parking brake

12

commercial vehicle

14

electrical control unit

16

Operating brake signal transmitter

18

Service brake circuit

18 '

Service brake circuit

20

service brake

22

another electrical control unit

24

Feststellbremsaktuator

24 '

Feststellbremsaktuator

24 ''

Feststellbremsaktuator

24 '

Feststellbremsaktuator

25

Feststellbremsaktuator

25

Feststellbremsaktuator

26

control signal

28

vehicle

28 '

vehicle

28 ''

vehicle

28 '' '

vehicle

30

CAN bus

32

vehicle axle

32 '

vehicle axle

32 ''

vehicle axle

34

braking system

36

valve module

36 '

valve module

36 ''

valve module

38

Manual control unit

40

tachograph

42

Vehicle CAN

44

Warning light

46

compressor

48

Compressed air treatment plant

50

container

52

pressure sensor

54

ABS modulator

54 '

ABS modulator

56

Speed sensor

56 '

Speed sensor

56 ''

Speed sensor

56 '' '

Speed sensor

58

Trailer control module

60

Pressure supply connection trailer

62

Trailer control terminal

64

vehicle speed

66

wheel speed

68

reference speed

70

slip velocity

72

Radumfangsbeschleunigung

74

contact pressure

76

pressure connection

78

Time t ₁

80

Time t ₂

82

Time t ₃

84

Time t ₄

86

Time t ₅

88

Time t ₆

90

Time t ₇

92

Time t ₈

100

normal operation

102

Service brake defective?

104

Braking initiated?

106

Start ABS control loop ECPB

Claims (9)

Method for operating a parking brake ( 10 ) with parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) and a service brake ( 20 ) comprehensive brake system ( 34 ) of a commercial vehicle ( 12 ), in the event of a service brake failure ( 20 ) the parking brake ( 10 ) a braking of the commercial vehicle ( 12 ), whereby those of the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) of the parking brake ( 10 ) applied braking forces via an ABS control loop and the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) are actuated in accordance with the specific braking forces to be applied, characterized in that - several vehicle axles ( 32 . 32 ' . 32 '' ) in any combination by the parking brake ( 10 ) and that - only the vehicle axles ( 32 . 32 ' . 32 '' ) of the parking brake ( 10 ), which are caused by the failure of the service brake ( 20 ) are affected. Method according to claim 1, characterized in that - the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) Spring brake cylinders comprise, wherein the applied braking forces are determined as ventilation rates for the spring brake cylinders and - that the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) are vented according to the determined deaeration rates. Method according to claim 1, characterized in that - the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) electric motor-operated parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ), wherein the applied braking forces as control pulses for the electric motor zuspannbaren Feststellbremsaktuatoren ( 24 . 24 ' . 24 '' . 24 . 25 . 25 ' ) and that - the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) are actuated according to the determined control pulses. Method according to one of the preceding claims, characterized in that the ABS control loop an individual control for one of the parking brake ( 10 ) braked vehicle wheel ( 28 . 28 ' . 28 '' . 28 ''' ), wherein the applied braking force for the braked vehicle wheel ( 28 . 28 ' . 28 '' . 28 ''' ) is determined separately. Method according to one of the preceding claims, characterized in that the ABS control loop, a "select low" control for one of the parking brake ( 10 ) braked vehicle axle ( 32 . 32 ' ), wherein the applied braking force of the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) of the braked vehicle axle ( 32 . 32 ' . 32 '' ) is determined by the highest applied braking force at which no vehicle wheel ( 28 . 28 ' . 28 '' . 28 ''' ) on the braked vehicle axle ( 32 . 32 ' . 32 '' ) blocked. Method according to one of the preceding claims, characterized in that the ABS control loop a modified individual control for one of the parking brake ( 10 ) braked vehicle axle ( 32 . 32 ' . 32 '' ), wherein the applied braking force of the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) of the braked vehicle axle ( 32 . 32 ' . 32 '' ) is determined by the highest applied braking force at which no vehicle wheel ( 28 . 28 ' . 28 '' . 28 ''' ) on the braked vehicle axle ( 32 . 32 ' . 32 '' ), and this applied braking force by the remaining parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) on the same braked vehicle axle ( 32 . 32 ' . 32 '' ) may be exceeded by a predetermined tolerance. Method according to one of the preceding claims, characterized in that the ABS control loop speed or rotational frequency characteristics of the vehicle wheels to be braked ( 28 . 28 ' . 28 '' . 28 ''' ) considered. Brake system ( 34 ) of a commercial vehicle ( 12 ) with a parking brake actuator ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) comprehensive parking brake ( 10 ) and a service brake ( 20 ), in the event of a service brake failure ( 20 ) the parking brake ( 10 ) a braking of the commercial vehicle ( 12 ), wherein the parking brake ( 10 ) an electronic control unit ( 14 ) which is adapted to provide an ABS control loop for actuating the parking brake actuators ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ), characterized in that the parking brake ( 12 ) is designed to multiple Vehicle axles ( 32 . 32 ' . 32 '' ) in any combination. Brake system according to claim 9, characterized in that the parking brake ( 10 ) is adapted, via the parking brake cylinder ( 24 . 24 ' . 24 '' . 24 ' . 25 . 25 ' ) simultaneously exert different braking forces.

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